JPH08122388A - Layer short detector - Google Patents

Abstract

PURPOSE: To detect the stage of partial discharge sustaining for a long term between the layers before making a transition to layer short by employing a variable voltage source as a test power supply and providing an electrode for scanning along the coil of an electric apparatus thereby detecting a high frequency potential oscillation caused by partial discharge of the electrode. CONSTITUTION: A test voltage equal to the interlayer withstand voltage is generated from a power supply 1 and applied directly to a coil 2 being inspected. If the interlayer insulation of the coil 2 is deteriorated, a partial discharge 3 takes place at a deteriorated part upon application of the withstand voltage. If an interlayer discharge 3 takes place, high frequency potential oscillation appears on a movable electrode 4 due to discharge 3 and the oscillation is introduced through a detection lead 11 to a partial discharge monitor 6. Consequently, the partial discharge part can be specified by scanning the electrode along the coil 2 using an insulation rod 10 and locating a position where the potential of the electrode is highest through the monitor 6. Since the voltage is applied only across the coil and not applied to the ground insulation 9, the interlayer insulation can be tested separately from the insulation 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing plant for electric equipment such as induction machines, induction voltage regulators, synchronous machines, transformers, and transformers for measuring instruments, or an inter-layer short circuit after these equipments are installed on site. The present invention relates to an interlayer short-circuit detection device for diagnosing.

[0002]

2. Description of the Related Art First, the distinction between interlayer insulation and ground insulation of electric equipment will be described with reference to FIG. As shown in FIG. 4A, the interlayer insulation 8 is applied to the outer periphery of the coil conductor 15 of the electric device, and the ground insulation 9 is applied after the coil is wound a required number of times. In such a winding structure, the interlayer insulation 8 is always destroyed (interlayer short circuit 12) before the ground insulation 9 is destroyed (ground fault 16).

The inter-layer short circuit 12 is, as shown in FIG.
The partial discharge 3 starts from the portion of the coil conductor 15 of these electric devices where the interlayer insulation is weak, but the conventional interlayer short-circuit detection device cannot detect the partial discharge at the initial stage because the voltage applied between the layers is small. From this partial discharge, Fig. 4 (c)
As shown in (1), if the inter-layer short-circuit accident 17 progresses, inter-layer short-circuiting occurs between the turns of the coil, and the impedance of the coil decreases, which facilitates detection, and various inter-layer short-circuit detection devices in this state have been proposed.

However, when the inter-layer short-circuit progresses, the impedance of the short-circuited portion is small, so that a large short-circuit current flows and the ground insulation 9 is rapidly deteriorated by heat. As a result, as shown in FIG. Then, a serious accident such as a ground fault accident 16 progresses.

Therefore, various conventionally proposed interlayer short-circuit detecting devices are difficult to put into practical use, and are not actually found as products. Moreover, it is not used in the current industrial field except for a special one as a protection relay for interlayer short circuit. At present, widely used are various ground fault detection relays, differential relays, overcurrent relays, and the like, which operate for the first time in a state in which an interlayer short circuit leads to a ground fault or an interphase short circuit.

Electrical equipment such as induction machines, induction voltage regulators, synchronous machines, transformers, and transformers for measuring instruments are widely used in various industrial plants including power plants, and they cannot be stopped socially. Since it has a serious effect, the initial state of the interlayer short-circuit is detected by using regular inspection before reaching the ground fault or short-circuit, and the coil in which the initial state of the interlayer short-circuit is detected is updated at the next regular inspection. Preventive maintenance measures are required.

Next, the principle of a typical conventional interlayer short-circuit detecting device will be described with reference to FIG. First, a surge voltage 19 is applied to the S-phase and T-phase tested coils 2 by an external surge voltage generator 18. If the S-phase and T-phase inspected coils 2 do not cause an interlayer short circuit, the lengths of both coils (surge propagation distance) and the impedance are basically equal, so the currents flowing through these inspected coils 2 are equal and the iron core 20 The magnetomotive forces due to these currents in the coil cancel each other out, and only a small current flows due to the electromagnetic coupling imbalance between the coils in the detection winding 21 wound around the iron core 20.

However, if an inter-layer short-circuit occurs in either the S-phase or T-phase coil to be inspected, the number of coil turns decreases, as is clear from the inter-layer short-circuit accident 17 in FIG. There is a difference in propagation distance. That is, there is a difference in the surge propagation state including reflection, which is detected as a difference in current. As can be seen from this, the conventional detection device detects not the initial state of the inter-layer short circuit but the state in which the inter-layer short circuit is completely completed. Ground insulation 9 in FIG. 4 (c)
Cannot be dealt with with enough time because it deteriorates. In addition, it is not possible to diagnose whether the deterioration state of the interlayer insulation is at a sound level, at a caution level, or at a fail level.

[0009]

Normally, the interlayer short circuit is caused by the deterioration of the interlayer insulation 8 at the beginning of the partial discharge 3 as shown in FIG. 4 (b).
start from. This partial discharge 3 lasts for a long period of time because the voltage applied between the layers during operation is small, so if this initial state is caught during the periodic inspection during this period, there will be time until the next scheduled stop or periodic inspection, and the coil can be updated. Here, as an example in which the interlayer voltage during operation is low, 6.6 KV-280
The interlayer voltage of the KW-8P induction motor is only about 8V.

The present invention has been made to solve the above problems, and an object thereof is to provide an interlayer short-circuit detecting device for detecting a stage of partial discharge that lasts for a long period between layers before shifting to interlayer short-circuit. .

[0011]

In order to achieve the above object, the first aspect of the present invention provides an interlayer short-circuit of an electric machine such as an induction machine, an induction voltage regulator, a synchronous machine, a transformer, a transformer for a meter. In the detection device, using a variable voltage power supply as a test power supply,
An electrode for scanning is provided along a coil of the electric device, and a partial discharge part of the coil of the electric device is specified by detecting high-frequency potential oscillation due to partial discharge of the electrode.

According to a second aspect of the present invention, in the interlayer short-circuit detecting device according to the first aspect, a variable frequency power source is used as a test power source. According to a third aspect of the present invention, in the interlayer short-circuit detecting device according to the first aspect, a variable voltage / variable frequency power source is used as a test power source.

According to a fourth aspect of the present invention, in the inter-layer short-circuit detecting device according to the first to third aspects, the location where the movable electrode that scans the inspection coil of the electrical equipment shows a maximum potential is the electrical equipment. It is characterized in that it is judged to be a partial discharge portion of the coil.

According to a fifth aspect of the present invention, in the interlayer short-circuit detecting device according to the first aspect to the third aspect, as the movable electrode for scanning the inspection coil of the electric device, the sound emitted from the partial discharge portion is detected. One or more movable microphones or ultrasonic sensors or AE (ACOUSTIC EMISSIO)
N) The partial discharge part of the electric device coil is specified by detecting with a sensor.

According to a sixth aspect of the present invention, in the interlayer short-circuit detecting device according to the first to third aspects, as a movable electrode for scanning the inspection coil of the electric device, the partial discharge site temperature is higher than that of other sound parts. It is characterized in that the partial discharge portion of the electric device coil is specified by detecting the increase in height using one or a plurality of movable infrared sensors.

According to a seventh aspect of the present invention, in the interlayer short-circuit detecting device according to the first to third aspects, the electromagnetic wave emitted from the partial discharge portion is used as a movable electrode for scanning the inspection coil of the electric device. The partial discharge part is specified by scanning the coil with one or a plurality of directional antennas.

According to an eighth aspect of the present invention, in the interlayer short-circuit detecting device according to the first to third aspects, a pulse of partial discharge in the coil to be inspected is used as a movable electrode for scanning the coil to be inspected of the electric device. It is characterized in that it is provided with a means for measuring the current that the vehicle rides on.

According to a ninth aspect of the present invention, in the interlayer short-circuit detecting device according to the first to third aspects, any one of a movable microphone, an ultrasonic sensor, an AE sensor, a movable infrared sensor, and a directional antenna sensor can be used. Or a combination of all.

[0019]

First, the principle of the present invention will be described. The voltage applied between the coil layers to be inspected is increased to facilitate detection of partial discharge. (Although the voltage applied between layers during operation is small, the permissible withstand voltage value of interlayer insulation is much higher than the interlayer voltage during operation, so it is possible to increase the voltage to make it easier to detect partial discharge.) Since the inter-layer voltage changes depending on the specifications of the machine to be inspected, the test power supply shall be a variable voltage power supply in order to accommodate them.

When the equipment to be inspected is a rotating machine, when a partial discharge location of the stator coil end portion (left and right ends of the coil) is specified, a high voltage is applied to the stator by a variable voltage power source while the rotor is inserted. Since the exciting impedance is large even when applied to the coil, the current flowing through the coil to be inspected 2 does not exceed the rated current, but it is necessary to remove the rotor when detecting partial discharge in the linear portion of the coil. In this case, the impedance seen from the power supply becomes only leakage reactance and winding resistance and becomes small, and when a test voltage is applied by a variable voltage power supply, the flowing current exceeds the rated current. In such a case, a variable frequency or variable voltage / variable frequency power source is used, and the coil impedance is increased by increasing the frequency so that the target test voltage is applied between layers.

When the power supply frequency is increased, the impedance of the coil increases in proportion to ωL, so that a high voltage can be applied. In addition, by using a variable voltage / variable frequency power supply, the applied interlayer voltage can be changed more flexibly from low voltage to high voltage, and the state of interlayer insulation is at a sound level or at a caution level. It can be diagnosed whether it is at the reject level or not, and the deterioration state of the interlayer insulation can also be diagnosed.
A movable power supply 4 that scans along the surface of the coil 2 to be inspected is provided to detect partial discharge before the transition to the interlayer short circuit.

When a partial discharge is generated between the layers, the electric field in the space around the layers is oscillated by superposition of a high frequency wave 23 as shown in FIG. Since the strength of this electric field attenuates in inverse proportion to the square of the distance, when the movable electrode 4 is brought into this electric field, electric charges are induced in the movable electrode 4 according to this electric field fluctuation. That is, the potential of the movable electrode changes according to the electric field oscillation of the partial discharge. Since the high frequency electric field vibration due to the partial discharge is attenuated in inverse proportion to the square of the distance as the distance from the partial discharge portion is increased, the coil is scanned by the movable electrode 4 and the portion where the potential of the movable electrode shows the maximum potential is the partial discharge. It can be determined as the location.

When a partial discharge is generated in the coil, a minute sound is generated from that portion due to the dielectric breakdown of the gas in the void. Therefore, in place of the movable electrode 4, a microphone, an AE sensor, or an ultrasonic sensor is used to scan the coil to detect this sound, and by monitoring the sensor output signals, the partial discharge location can be specified. Further, by using a plurality of these sensors and detecting the time delay of the sound reaching each sensor, the partial discharge portion can be specified more accurately.

If partial discharge occurs in the coil, there is power loss. This means that heat is generated at the partial discharge location, so that the temperature at the location where the partial discharge occurs is higher than that at the other coil portions. Therefore, the partial discharge portion can be specified by scanning the coil with an infrared sensor instead of the movable electrode 4.

When a partial discharge is generated in the coil, electromagnetic waves are radiated from the partial discharge portion so that noise due to the partial discharge enters the radio due to the partial discharge of the power transmission line. Therefore, by scanning the coil with an antenna having directivity instead of the movable electrode 4, the partial discharge portion can be specified.

When partial discharge occurs in the coil, pulsed high frequency current is superposed in the coil. Therefore, if the current flowing through the coil to be inspected is monitored on either side of the coil (on the side where the voltage is applied or on the opposite side), it is found that partial discharge has occurred at any point of the non-inspected coil. The detection accuracy of the partial discharge portion can be improved by any combination or all combinations of the above various detection methods.

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of the first embodiment of the present invention, in which FIG.
Is a configuration diagram, and FIGS. 8B and 8C are a side view and a front view in which a movable voltage power source is placed on a coil to be inspected.

As shown in FIG. 1, the test apparatus main body 7 of this embodiment comprises a movable voltage power source 1 and a partial discharge monitoring apparatus 6. A test voltage is generated from a movable voltage or a variable frequency or a variable voltage / variable frequency power source 1 and directly applied to the coil 2 to be inspected. If there is partial discharge 3, partial discharge 3
The high-frequency potential vibration 5 due to is detected by the movable electrode 4 that scans over the coil 2 to be inspected, and is guided to the partial discharge monitoring device 6.

As shown in FIGS. 1 (b) and 1 (c), a coil interlayer insulation 8 is provided on the outer circumference of the coil 2 to be inspected, and a ground insulation 9 is further provided on the outer circumference thereof. The movable electrode 4 for scanning over the ground insulation 9 is arranged. The movable electrode 4 detects a partial discharge inside the coil while scanning along the coil 2 to be inspected by the insulating rod 10.

Next, the operation of this embodiment will be described.
By generating a test voltage of an interlayer withstand voltage value by the power supply device 1,
The generated voltage is directly applied to the coil to be inspected 2. If the interlayer insulation 8 of the coil to be inspected 2 is deteriorated, the partial discharge 3 is generated at the deteriorated portion by multiplying the withstand voltage value. If partial discharge occurs between the layers, high-frequency potential vibration due to partial discharge appears on the movable electrode 4, and is guided to the partial discharge monitoring device 6 through the detection lead 11. Therefore, the partial discharge portion can be specified by scanning the movable electrode 4 along the coil 2 to be inspected by the insulating rod 10 and searching for a position where the potential of the electrode is maximized by the partial discharge monitoring device 6. . Further, since the applied voltage is applied only between the coils and is not applied to the ground insulation 9, the insulation state between layers can be tested separately from the ground insulation 9.

As described above, according to this embodiment, since the partial discharge at the initial stage before the interlayer short circuit is detected, it is possible to plan the replacement of the deteriorated coil with a time margin. Any of a sensor that detects sound, an infrared sensor that detects temperature, and an antenna that detects electromagnetic waves may be used in place of the movable electrode 4 of FIG. 1, and any combination of these sensors or all of them may be used. The same effect as in the above embodiment can be obtained by using the combination.

FIG. 2 is a block diagram of the second embodiment of the present invention. In the figure, in this embodiment, a variable voltage or variable frequency or variable voltage / variable frequency power source 1 for generating a test voltage and a non-inductive resistor 13 are provided between the power source 1 and the voltage application point. . The voltage across the non-inductive resistor 13 is connected to the current monitoring device 14. The R phase and S phase of the coil to be inspected 2 are connected in series. Reference numeral 4 denotes a movable electrode that scans the coil to be inspected, a microphone, an ultrasonic sensor, an AE (ACOUSTIC EMISSION) sensor, an infrared sensor, an arbitrary combination of antennas, or a sensor combining all of them. Lead 1 of these sensors
1 is connected to the partial discharge monitoring device 6. Reference numeral 12 is an interlayer short-circuit location, and 7 is a test apparatus main body.

In addition to the partial discharge detection function of the first embodiment, this embodiment has an interlayer short circuit detection function capable of detecting the state of transition to an interlayer short circuit. Since the former partial discharge detection function has been described in the first embodiment, the latter interlayer short-circuit detection function operation will be described.

A current obtained by dividing the voltage applied from the test power supply 1 by the impedance of the coil under test flows through the non-inductive resistor 13. A voltage proportional to the current appears at both ends of the non-inductive resistor 13, and can be monitored by the current monitoring device 14.

FIG. 2 shows the state in which the R-phase and S-phase coils are being tested, but the connection is changed and the voltages are similarly applied to the S-phase and T-phase coils and finally to the T-phase and R-phase coils. It is possible to judge in which phase the interphase short circuit occurs from the magnitude of the current of the current monitoring device 14 at each time. For example, R
If an interphase short circuit occurs in the phases, the impedance of the R phase becomes small. If this is Z1 and the impedance of the sound coil is Z2, impedance at R phase-S phase test = Z1 + Z2 (small impedance) Impedance at S phase-T phase test = 2Z2 (large impedance) T phase-R phase test Impedance at time = Z1 + Z2 (small impedance). The instructions of the current monitoring device during the R phase-S phase test and the T phase-R phase test are the same, and the instructions of the current monitoring device during the S phase-T phase test are the R phase-S phase and T phase-R phase tests. If it is smaller than the current instruction at that time, it can be determined that there is an interphase short circuit in the R phase. Alternatively, the judgment can be made by comparing with the impedance value in the test report. The location where the inter-layer short circuit occurs is determined by the movable electrode that scans over the coil to be inspected, microphone, ultrasonic sensor, AE (ACOUSTIC EMISSIO).
N) Detect any combination of sensors, infrared sensors, antennas or all combinations.

FIG. 3 shows a third embodiment of the present invention, which is different from the second embodiment in that the coil to be inspected has a triangular connection and the non-inductive resistance 13 is provided for each of the two test coils. They are attached one by one and are led to the current monitoring device 14.

In this embodiment, a non-inductive resistance is placed between the R-phase and T-phase coils, which are the coils to be inspected, and the ground, and the voltage across the non-inductive resistance is input to the current monitoring device 14 so that the magnitude of the current can be compared. Keep it.

By making the connection in this way, the magnitude relation of the impedance of each phase winding can be determined by the current monitoring device. The figure shows the case of R phase and T phase, but by changing the connection and measuring T phase and S phase, it is possible to know in which phase the interlayer short circuit occurs.

The location where the interlayer short circuit occurs is a movable electrode for scanning the coil to be inspected, a microphone, an ultrasonic sensor, A
E (ACOUSTIC EMISSION) sensor, infrared sensor,
Any combination or combination of antennas can be detected.

[0040]

As described above, according to the present invention,
Since it is possible to detect the partial discharge in the initial stage before the interlayer short circuit occurs, it is possible to plan the update of the deteriorated coil with a sufficient time, which is an excellent effect.

[Brief description of drawings]

1A is a configuration diagram of an embodiment of the present invention, and FIGS. 1B and 1C are a side view and a front view in which a movable voltage power source is placed on a coil to be inspected.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a diagram for explaining ground insulation and interlayer insulation of an electric device coil, ground fault, and interlayer short circuit.

FIG. 5 is a circuit diagram for detecting a conventional interlayer short circuit.

FIG. 6 is a waveform diagram for explaining high frequency vibration due to partial discharge.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power source, 2 ... Inspected coil, 3 ... Partial discharge, 4 ... Movable electrode, 5 ... High frequency potential vibration, 6 ... Partial discharge monitoring device, 7
… Test equipment body, 8… Coil layer insulation, 9… Ground insulation,
10 ... Insulating rod, 11 ... Sensor lead, 12 ... Interlayer short circuit, 13 ... Non-inductive resistance, 14 ... Current monitoring device, 15 ... Coil conductor, 16 ... Ground fault accident, 17 ... Interlayer short circuit accident, 18
… Surge voltage generator, 19… surge voltage, 20… iron core, 21… detection winding.

Claims (9)

[Claims] 1. In an inter-layer short-circuit detection device for electric equipment such as induction machines, induction voltage regulators, synchronous machines, transformers, transformers for measuring instruments, etc., a variable voltage power supply is used as a test power supply, and along a coil of the electric equipment. An inter-layer short-circuit detection device is characterized in that an electrode for scanning is provided, and a high-frequency potential oscillation due to a partial discharge of the electrode is detected to identify a partial discharge portion of the electric device coil. 2. The interlayer short-circuit detection device according to claim 1, wherein a variable frequency power supply is used as a test power supply. 3. The interlayer short-circuit detection device according to claim 1, wherein a variable voltage / variable frequency power supply is used as a test power supply. 4. The interlayer short-circuit detecting device according to claim 1, wherein the movable electrode scanning the inspection coil of the electric device shows a maximum potential at a partial discharge point of the electric device coil. An inter-layer short circuit detection device characterized by determining that there is. 5. The interlayer short-circuit detecting device according to claim 1, wherein one or a plurality of movable microphones that emit sound emitted from a partial discharge portion are used as movable electrodes that scan the inspection coil of the electric device. Alternatively, an interlayer short-circuit detection device is characterized in that a partial discharge part of the electric device coil is specified by detecting using an ultrasonic sensor or an AE sensor. 6. The interlayer short-circuit detecting device according to claim 1, wherein the movable electrode for scanning the inspection coil of the electric device has a partial discharge site temperature higher than that of other healthy parts. Alternatively, an interlayer short-circuit detection device is characterized in that a partial discharge part of the electric device coil is specified by detecting using a plurality of movable infrared sensors. 7. The inter-layer short-circuit detection device according to claim 1, wherein one or a plurality of directivities of electromagnetic waves radiated from the partial discharge portion are used as movable electrodes for scanning the inspection coil of the electric device. An interlayer short-circuit detection device, characterized in that a partial discharge part of the electric device coil is specified by scanning the inspection coil with a certain antenna. 8. The interlayer short-circuit detecting device according to claim 1, wherein the movable electrode for scanning the coil to be inspected of the electric device measures a current on which a partial discharge pulse in the coil to be inspected rides. An inter-layer short-circuit detection device, characterized in that: 9. The interlayer short-circuit detecting device according to claim 1, wherein a movable microphone, an ultrasonic sensor, an AE sensor, a movable infrared sensor, and a directional antenna are combined arbitrarily or in combination. An inter-layer short-circuit detection device characterized by the above.